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Steam Hoover

Discussion in 'Steam Traction' started by Bikermike, Jan 2, 2021.

  1. Bikermike

    Bikermike Member

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    Imagine if the WCML electrification was coming, but dieselisation was delayed. So you need a last hurrah of steam with a chunk more power. What would you do?
    My thoughts
    As a Duchess boiler seems to be as big as you can get (optimal length/diameter ratio) in the loading gauge, more boiler means smaller wheels. 8 coupled at 6' dia?
    This means faster wheel rotations, so roller bearings all round.
    But a duchess boiler is the limit of a single fireman, so my big idea is supplementary gas burners (which may also be handy to keep smoke down at termini).
    Gas-flow the heck out of it
    Also, with smaller wheels, cutting down reciprocating mass helps even more, so Caprotti valve gear. Would 1950s electronic technology permit more accurate valve events?
    How about poppet valves post WW2 experience?

    The basic premise is "how could you squeeze that bit more out of British- sized steam?
    Could you shrink a Chapelon compound down?
    Feed-water heaters?
     
  2. Allegheny

    Allegheny Member

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    The usual suggestion is better draughting.
     
  3. Bikermike

    Bikermike Member

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    As in blast-pipe etc?

    One thing that I would have looked at is coupling rods - how much mass could you lose from them?
     
  4. 61624

    61624 Well-Known Member

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    Turbine-electric?
     
  5. 242A1

    242A1 Member

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    Simply include the best tried and tested thinking from the 1930s and make certain that the engineers involved were not slaves to the "not invented here" school.
    Pity we could not have trialed the 141R and learned something from it since power is only one part of the equation.
    If this situation, this alternate history line, had come about it is unlikely that you would get anything better than what existed at the time.
     
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  6. martin1656

    martin1656 Resident of Nat Pres Friend

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    Logically, a steam turbine powering electric traction motors would have been the way forward, as your using both technologies, either oil firing, or liquid coal to fire the boiler, and of course that would have enabled a cab at either end even if the fireman only operated the controls from one end unless it became possible to remotely fire the engine from both cabs, was a boiler ever designed with a firebox at either end? or a central firebox, with remote linkages etc to operate burners, dampers etc ?
     
  7. Allegheny

    Allegheny Member

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    If you obtain a copy of "Red Devil and other tales from the age of steam" by David Wardale, it details all sorts of changes that he applied to various locomotives, in particular a Class 25 4-8-4 on the South African Railway.
     
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  8. Jamessquared

    Jamessquared Nat Pres stalwart

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    I thought the usual suggestion was double heading?

    Tom
     
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  9. Russ Bulley

    Russ Bulley New Member

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    The one thing that did not happen was higher temperatures and pressures which you need for greater efficiency. But given that I have been reading all the work that has been done in recent years on drafting, amazing results have been achieved. So shorter exhaust pipes, with smooth ceramic coatings (like we do for turbo chargers), very accurate valve events, maybe electronically controlled to marry up with torque and cut off.

    And of course condensing. It is obvious that exhausting to a vacuum would be a major step up.

    Russ
     
  10. ghost

    ghost Part of the furniture

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    I thought it was to paint it in BR livery?

    Keith
     
  11. johnofwessex

    johnofwessex Part of the furniture

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    Wardale is interesting, not so much because of the engineering but because he understands the context in which the steam locomotive operates.

    So, the challenge ISNT to build the biggest fastest loco we can, its to provide a commercially attractive long distance steam hauled service in the mid 1960's

    First question is what will that service look like, do we want a frequent service of light trains or a less frequent service of heavy ones?

    What other things do we need to do in connection with this service? If it is having to be threaded through large numbers of slow moving freights then we will need to do something about these.

    What about the environment around the railway? I understand that there were major issues about manpower because of the working conditions in steam sheds and on the footplate so we need decent working conditions for staff. Similarly railway stations were dirty, unattractive places - largely as a result of steam locomotives.

    An obvious starting point it seems to me would be to have a good look at the Norfolk & Western in terms of what could be done with modern steam locomotives and decent working conditions, before you then start on David Wardales work, nit just the engineering but the insight.

    Given that a major cause of inefficency in steam locomotives is the 'unburnt fuel loss' then not only will Wardales work improve the performance if the loco but of the surrounding environment
     
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  12. johnofwessex

    johnofwessex Part of the furniture

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    What, two H class?
     
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  13. Jamessquared

    Jamessquared Nat Pres stalwart

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    Unburnt fuel is one loss, but the real killer is losing the latent heat of evaporation of the steam: to solve that you need a condenser and heat recovery, but most such efforts on rail vehicles weren't very successful, primarily because of the design difficulties within a given spatial envelope, and also the need to find an alternative means of draught. It also increases the dead weight to haul around, i.e. reduces the remunerative load.

    You are right to point out the context though. So what do we need this super-powerful locomotive for? You've really got three options: pull a heavier train at the same speed; pull the same weight train faster; or accelerate faster.

    Of those, "pull a heavier train at the same speed" - that assumes that there is additional traffic to be had; more seriously, it also relies on being able to accommodate a longer train. To take Waterloo as an example, the longest possible train was about 13 carriages (and even then only with special operating practice), so there is no scope for bigger trains. Other stations might be a bit more flexible, but operating conditions grew up in Britain tended to favour frequent, short trains, for which huge power isn't required. Ultimately, two Black 5s are more useful than one Duchess.

    What about pull the same weight faster? There you get into limits of balancing, bridge stress, impact on the permanent way etc., as well as lubrication. 100mph was achieved quite regularly and safely, but much faster started getting perilous (witness the inaugural run of the Coronation smashing crockery as it approached Crewe; or the ignominious end to Mallard's record breaking run). So really the limits of safe operation of a steam locomotive are probably not much above 100mph, whereas alternative traction without reciprocating masses can comfortably run much quicker.

    That then leaves acceleration, which given the relative short start to stop distances run in Britain, is actually a more propitious route to high average speed than trying to maximise top speed. But were I asked to design a quick accelerating train, I might be inclined to look at the train as much as the motive power: a few tons taken out of each carriage would potentially be an easier route to quick acceleration than a more powerful locomotive.

    Tom
     
  14. MellishR

    MellishR Part of the furniture Friend

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    The general story of passenger train operations in Britain for much of the 19th and 20th centuries was progressively heavier trains and higher speeds. Yet many routes now (or rather not right now, but before the pandemic struck and perhaps in the near future) have frequent short trains, much like the Midland Railway's service pattern. Did things change because there are now no very slow freight trains and therefore more paths available for passenger trains? About the only exception to short passenger trains that comes to mind is the Caledonian Sleeper, with (in normal conditions) two very long trains each way each night, each of them dividing/combining to serve different destinations.
     
  15. Jamessquared

    Jamessquared Nat Pres stalwart

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    That would be nice!

    Tom
     
  16. pete2hogs

    pete2hogs Member

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    You don't need more power. WCML trains after electrification were short and light compared to the trains the Duchesses and Peppercorn A1's were designed for. Recast the timetables and build 80 A4/1's with roller bearings (on the conjugated gear as well) and all the 50's improvements - they would do the job fine. Or, to be fair, another 50 Duchesses, but they are actually more powerful than necessary - the existing squad would have been fully employed on the heavy but slower overnight sleepers.

    The rebuilt Merchant Navies would have been suitable as well, but they were needed on the Bournemouth run.
     
    Last edited: Jan 3, 2021
  17. 242A1

    242A1 Member

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    There are a substantial number of other books that are helpful as a guide to understanding what is possible. For those engaged in locomotive design during the period in question there were other problems, one of the main ones was the unwillingness to challenge their own beliefs. This trait goes back many years.
    When Chapelon carried out his first rebuild in the 1920s the transformed 3566 matched its predicted performance when out on trials. It achieved 3,000 ihp in the speed range 75 -80 mph and delivered a reduction in fuel consumption (related to power output) of some 40%. The original output figure of the unrebuilt design at high speeds was 1,850 ihp. There was considerable disbelief in this achievement but as 3566 and its sister rebuilds continued to confirm these figures they came to be accepted even if the methods used to deliver them were not well understood. A few slight changes later and these rebuilt Pacifics were achieving 3,700 ihp and these figures were not transitory but sustained. These rebuilds weighed 100.39 tons, a Princess Coronation weighs 105.25 tons, a Britannia 94 tons, 71000 101.25 tons and the British engines were new designs which appeared after the rebuilds.
    Chapelon gained a number of admirers and disciples throughout the world but none here, particularly during the period in question, until well after steam on the BR mainline had vanished.
    If you want more powerful engines these could have been achieved (given the people) but in order for them to be able to deliver the improvements in on the road performance that you might be seeking you might need more than just the locomotives. There are facilities and crew training to consider and these things have a cost implication. The earlier mentioned 141R was an engine which was well suited to working well in an existing operating environment; it was robust and easily maintained, and was designed with good accommodation for the crew in mind. It might not have been as powerful as the French equivalent, it might not have been as powerful as a Pacific nor as fast but it had a balance of qualities and the tractive effort and adhesive weight made it good at handling trains and so you might settle for more dependably available power as opposed to simply more power.
     
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  18. Cartman

    Cartman Member

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    A few black fives would probably have done the job
     
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  19. clinker

    clinker New Member

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    Perhaps 'Decapod' was the way to go after all...................?
     
  20. Hermod

    Hermod New Member

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    Last edited: Jan 3, 2021
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